Foundry

Almost none, except for long and excessively thin shapes.

Limited by the supply of molten metal and capacity of parts handling.

Yes, virtually all types, especially beneficial for hard or tough alloys with poor machinability.

Foundry patterns are generally more cost-effective, with design changes easier in early production stages.

• The casting leads to a solidification structure with the inclusion of defects

• the durface roughness is comperatively very high

• The dimensional tolerances are low (=bad)

1. Melting

2. Secondary metallurgy

3. Casting

4. Extraction

• Arc

• Induction

• Crucible

• Cupola

• Cast iron

• Steels

• Copper based alloys

• Aluminium alloys

• Magnesium alloys

• Zinc alloys

• Nickel alloys

• Electric arc furnace

• Induction furnace

  
  

• Cupola furnace

• Rotary kiln furnace

  
  

• Rotary kiln furnace

• Induction furnace

Vacuum induction furnace

The metal charge is heated by an alternating electromagnetic field, which induces an induction current

The rotary kiln furnace is a furnace for small and medium foundries which is rotated. The metal is heated by the gases that are passed through it.

• Viscosity

• temperature

• chem. composition

"superheat" refers to the temperature difference between the actual temperature of a molten metal or alloy and its liquidus temperature

• oxide films on the surface of the molten metal increase surface tension and therefore fluidity

• high surface tenssion of the metal reduces flluidity

• Thermal properties

  • diffusivity

• Evaporation of surface from the water

• surface roughness

• Use of reactive coatings

• Resistance given by entrapped air

1. Mold creation and metal melting

2. Pouring into mold

3. Solidification and cooling

4. shakeout and removal of risers and gate

5. Cleaning and finishing

Pattern, core, flask (cope and drag), and gating system.

A core is used to create internal cavities and complex shapes within the casting.

Wood, metal, and plastics.

The Volume to casting flow ratio V/S

The casting flow S is defined by the Volume per time and speed (V/(t*v))

The casting modulus helps determine if a casting will solidify without defects, shrinkage, porosity or hot tearing.

1. Calculate the casting modulus of each part

2. each part can feed the adjacent one if Mn>1,1 Mn+1

3. Feeders need to be used if Mn>1,25 Mn+1

• silica sand 83%

• Binder 8.5 % (clay, betonite)

• Additives 5% (carbon powder)

• Water 3.5%

• higher cooling rate

• better liquid fluidity

• better precision

• good surface finish

• high dimensional accuracy

• good surface finish

• expensive

• shell mould casting

• low pressure casting

• die casting

• squeeze casting

• semisolid metal forming

• 5000 for steel casting

• 20000 for cast iron casting

• 25000 parts for CU alloy

• 100000 parts for Al alloy

• metallic mould

• high cooling rates

• good surface finish

• tight tolerances

• uniform properties

• high productivity

• non ferrous alloys

Al, Mg, Cu

20-200

1. Die preperation (cleaning, lubrication)

2. Chamber pre-fill

3. Cavity fill low pressure

4. Cavity fill high pressure

5. Dwelling for solidification

6. Die opening and ejection

7. plunger return

• near net shape

• no porosity

• fine microstructure

• mechanical properties similar to forging

• automated process

• high productivity

the die pressure resitance

the metal is casted in between T solidus and T liquidus

• homogenous microstructure

• laminar filling of the cavities => lower gas entrapment

• casting as well as wrought alloys can be used

• low shrinkage in solidification

• process suitable for composite materials

• Lost Foam Process

• Investment casting

• Lamina metal flow

• rapid cooling

• polystyrene pattern

• pattern fabricated out of wax, which is melted out

  
  

• scrap

• pure Aluminum

• alloying metals (Zn, Mg, Sn)

• Master alloys

• Rotary kiln furnace

• induction furnace

1. melting furnace

2. melt treatment

3. Direct chill casting

4. Homogenization

5. Homogenization semis

6. semi finished part

7. final manufactoring

The treatment is carried out to improve workability, eliminate microsegregation, dissolove precipitates.

• fluxes are introduced to the molten bath to improve the final product.

• fluxing is salt based: NaCL, NaF, AlCl

• rotary flux injection system

  • introduction by spinning rotor, which leads to shearing of the salts

• TAC process

  • introduction through a carrier gas that spreads the AlF3 powder through a rotary system.

  • conducted while metal is on way to casthouse

• gas treatments

  • inert gas (argon, nitrogen)

  • reactive gas (Chlorine based)

• vacuum treatment

The hydrogen diffuses into the inert gas bubbles.

• increased mechanical properties

• improved castability

• better results from heat treatment

• better machineability and plastic deformation

• rapid cooling

• stirring (electromagnetic, ultrasound or gas)

• refining additions (Ti alloys, salts, B, Zr)

Lower liquidus temperature and no “mushy zone”

• better fluidity cause of eutectic

• high resistance to corrosion

• good weldability

• low thermal expansion

• poor mechanical properties

• poor machineability (brittleness and coarse microstructure)

• filter cake

  • filtered out particles start filtering themselfs

• depth filtration (most commonly used)

  • long path of filtering

  • higher possibility of filtering inclusions out

• metal or fiberglass meshes

• Bonded ceramic particle filters of either AL2O3 or SiO2

• Ceramic foam filters

  • coating of polyurethane with ceramic slurry and firing out

  • materials: Zr, Al, Cr2O3